Identification of aroma active compounds in Shanxi aged vinegar and tracing the source in the entire production process.

The aroma-active compounds (AACs) of traditional vinegars are formed through complexed pathways. Moreover, their source is not clear yet. The composition of AACs throughout the entire process of Shanxi aged vinegar (SAV) production from the raw materials, alcohol fermentation (AF), acetic acid fermentation (AAF), fumigation and aging stages were analyzed. A total of 121 AACs were determined by GC × GC-O-TOF-MS, of which 88 were identified by GC-MS/MS. There were 27 and 41 AACs (FD ≥ 400) detected in before-aging and after-aging SAV, respectively. Furthermore, it can be concluded the AAF and fumigation were the main sources of AACs. Also, the AAF was the main source of the compounds with caramel, creamy, floral, fruity, sour, cheesy notes, while the compounds owned roasted, nutty, spicy and woody aromas mainly came from fumigation. Finally, the potential transformation pathway of AACs was mapped and discussed. Overall, GC × GC-O-TOF-MS was a useful technique to enrich the AACs of SAV.